AJ lost his heavyweight world titles in a stunning upset as he was stopped by rank outsider Ruiz at Madison Square Garden on Saturday night.
It was a fight the British star was never supposed to lose and it looked to be heading the way everyone expected when he knocked down his opponent in round three.
Joshua, though, was sent to the canvas four times and eventually stopped in the seventh as Ruiz pulled off one of the greatest shocks in boxing history.
And former IBF cruiserweight champion Glenn McCrory thinks this could be it for the 29-year-old.
“He’s bottom of the pile. He got beaten up by Andy Ruiz,” McCrory told talkSPORT.
“I think he’s finished. It’s not just the defeat, anybody can get defeated, but the nature of it.
“Andy Ruiz is not an elite athlete, he is not a heavyweight great. He will not go down in icons of legends at all but he is a tough kid and he seized his opportunity.
“I have to say well done Andy Ruiz.
“Anthony Joshua let himself and the nation down.
“If you take your eye off the ball then you lose. It’s as simple as that.
“It’s not rocket science. It’s the fact you think you can win and you just turn up and don’t do the work.
“I said this weeks ago he is training on Miami Beach. What’s he training on Miami Beach for? Boxers don’t do that with all those distractions.
“What on earth were they thinking about?
“It was absolute total humiliation. This was a fight that was an easy, easy fight.
“Let’s get this right. It was simple and he blew it.”